The second choice that you give up when choosing the best; for example, in choosing a better-paid job further away, commuting time is the opportunity cost. Carlino (1985; cited in Desmet and Fafchamps (2005) J. Econ. Geog. 5, 3) argues that, though the cost of moving goods has gone down through improved technology, the cost of moving people—as measured by the opportunity cost of time—has gone up. Baldwin and Okubo (2006) J. Econ. Geog. 6, 3 show that regional policies tend to attract the least productive firms since these have the lowest opportunity cost of leaving an agglomerated region; ‘the result is a “sorting effect” ’. See Willis et al. (1998) Transp. Res. D 3, 3 on land prices and social opportunity cost.